C/C friction disks each constituted by a carbon fiber preform densified by a carbon matrix, are commonly used in brakes for aircraft and for competitive motor vehicles.
The behavior of carbon/carbon composite materials rubbing in oil against one another or against a metal, such as steel, makes it possible to consider using these materials in applications such as those mentioned above. C/C materials then present little wear and a coefficient of friction that is stable. In addition, they are relatively insensitive to speed effects, or to variations of unit-area pressure. Furthermore, friction with C/C materials in oil depends little on the nature and the viscosity of the oil in question.
Thus, document U.S. Pat. No. 5,409,428 describes an automatic gear box using C/C disks rubbing against metal disks in oil.
In friction devices using C/C disks, the disks are generally connected to the driving or rotary members and to the driven or fixed members by crenellations formed at the peripheries of the disks. In order to be able to take up forces at the crenellations, without running the risk of damage, it is necessary to use disks that are of sufficient thickness, thereby significantly increasing cost because of the high cost price of C/C materials.